Age-related macular degeneration (AMD) is the leading cause of blindness among the elderly, yet patients with early disease are without therapy. To address this shortcoming, this proposal focuses on early disease. Two key events in early AMD are retinal pigment epithelial cell (RPE) dysfunction and drusen biogenesis. Inadequately neutralized reactive oxygen species (ROS) and dysregulated innate immunity interact together to play a pivotal role. Central to oxidative homeostasis, especially in mitochondria, is the Nrf2 transcription factor, which controls the most comprehensive antioxidant response system. Nrf2 signaling can become impaired with aging and/or smoking. The objective of this proposal to define how Nrf2 protects against RPE mitochondrial dysfunction and unregulated innate immunity. The hypothesis to be tested is that that impaired Nrf2 signaling induces mitochondrial and RPE dysfunction that results in an oxidative, inflammatory, and pathologic microenvironment. The proposed specific aims are: 1. Determine the extent that impaired Nrf2 signaling leads to un-neutralized mitochondrial ROS and RPE dysfunction with cigarette smoke exposure. Our hypothesis is that impaired Nrf2 signaling in the RPE from aging and chronic smoking reduces mitochondrial antioxidant defense resulting in inadequately neutralized ROS and RPE dysfunction. 2. Determine the extent that impaired Nrf2 signaling decreases mitophagy, and results in RPE dysfunction with cigarette smoke exposure. Our hypothesis is that impaired Nrf2 signaling in the RPE from aging and chronic smoking decreases mitophagy, cumulatively increasing the number of dysfunctional mitochondria and inadequately neutralized ROS, resulting in RPE dysfunction. 3. Determine the extent that impaired Nrf2 signaling disrupts regulation of innate immunity. Based on our work showing C3a and IL-1b generation by CS and Nrf2 deficiency, our hypothesis is that impaired Nrf2 signaling magnifies oxidative stress, which activates the inflammasome to promote a pro-inflammatory microenvironment with accumulation of macrophages with impaired function. These contributions are significant because they will establish Nrf2 as a treatment target for early AMD. The research is innovative since it will investigate understudied (decreased Nrf2 signaling on mitochondrial antioxidants and mitophagy), unresolved (inflammasome and macrophage function) and unique (the synergy of ROS and innate immunity) factors on RPE and macrophage function using unique, state-of-the- art genetic mice with fresh, but decisive factors that have not been previously tested. Macrophages will be studied from a new perspective that defines both phenotype and function since both are influenced by their surroundings. Our discovery of reduced Nrf2 with aging and CS, which generates C3a and IL-1b, a key substrate of the inflammasome, and the proposed studies, which will link complement with the inflammasome, macrophage function, and an AMD phenotype, is highly innovative. Targeted therapy that reinvigorates Nrf2 to maintain oxidative homeostasis and protective innate immunity is expected to result from this work.

Public Health Relevance

Age-related macular degeneration (AMD), the most common cause of blindness among the elderly, is triggered by oxidative stress, which imbalances innate immunity. Retinal pigment epithelial (RPE) cell damage is a key event in early disease that is regulated by the transcription factor Nrf2, which controls the cell's most comprehensive known antioxidant system. This proposal will study how aging and oxidative stress impair Nrf2, which increases oxidative stress through mitochondrial damage, and the development of RPE damage, deregulation of innate immunity, and development of early AMD.

National Institute of Health (NIH)
National Eye Institute (NEI)
Research Project (R01)
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Special Emphasis Panel (ZRG1-BDCN-H (02))
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Shen, Grace L
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Johns Hopkins University
Schools of Medicine
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Cano, Marisol; Wang, Lei; Wan, Jun et al. (2014) Oxidative stress induces mitochondrial dysfunction and a protective unfolded protein response in RPE cells. Free Radic Biol Med 69:1-14
Chen, Chen; Cano, Marisol; Wang, Joshua J et al. (2014) Role of unfolded protein response dysregulation in oxidative injury of retinal pigment epithelial cells. Antioxid Redox Signal 20:2091-106
Wang, Lei; Cano, Marisol; Handa, James T (2014) p62 provides dual cytoprotection against oxidative stress in the retinal pigment epithelium. Biochim Biophys Acta 1843:1248-58
Wang, Lei; Kondo, Naoshi; Cano, Marisol et al. (2014) Nrf2 signaling modulates cigarette smoke-induced complement activation in retinal pigmented epithelial cells. Free Radic Biol Med 70:155-66
Ebrahimi, Katayoon B; Fijalkowski, Natalia; Cano, Marisol et al. (2014) Oxidized low-density-lipoprotein-induced injury in retinal pigment epithelium alters expression of the membrane complement regulatory factors CD46 and CD59 through exosomal and apoptotic bleb release. Adv Exp Med Biol 801:259-65
Cruz-Guilloty, Fernando; Saeed, Ali M; Duffort, Stephanie et al. (2014) T cells and macrophages responding to oxidative damage cooperate in pathogenesis of a mouse model of age-related macular degeneration. PLoS One 9:e88201
Xu, Zhenhua; Wei, Yanhong; Gong, Junsong et al. (2014) NRF2 plays a protective role in diabetic retinopathy in mice. Diabetologia 57:204-13
Valapala, Mallika; Edwards, Malia; Hose, Stacey et al. (2014) Increased Lipocalin-2 in the retinal pigment epithelium of Cryba1 cKO mice is associated with a chronic inflammatory response. Aging Cell 13:1091-4
Sachdeva, Mira M; Cano, Marisol; Handa, James T (2014) Nrf2 signaling is impaired in the aging RPE given an oxidative insult. Exp Eye Res 119:111-4
Barnett, Brad P; Handa, James T (2013) Retinal microenvironment imbalance in dry age-related macular degeneration: a mini-review. Gerontology 59:297-306

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